Knee sizing and balancing instrument

ABSTRACT

An orthopedic instrument for knee arthroplasty includes an anterior-posterior sizer assembly, a tensor assembly and a rotation mechanism. The sizer assembly includes a stylus, a sizer body including medial and lateral posterior feet extending substantially perpendicularly from the sizer body, and a sizer slider that can slide relative to the sizer body along a medial-lateral direction relative to a patient&#39;s knee. The tensor assembly includes a tensor frame having a central portion, medial and lateral wings extending at an angle from the central portion, and medial and lateral posterior feet extending substantially perpendicularly to the central portion. The rotation mechanism includes a portion coupled to the tensor frame of the tensor assembly and a portion coupled to the sizer body. The rotation mechanism is configured to rotate the medial and lateral posterior feet of the sizer body relative to the tensor frame toward a lateral side of the patient&#39;s knee.

FIELD

The present disclosure relates to an integrated knee sizing andbalancing instrument and associated methods.

INTRODUCTION

During knee arthroplasty various sizing, balancing and trialingprocedures are performed before an implant is selected and/or implanted.For example, the femoral component is carefully sized and theanterior-posterior dimension of the resected distal femur is determinedusing an anterior-posterior (AP) sizer. Additionally, knee balancing isperformed to achieve equal flexion gaps and proper tension of the medialand lateral ligaments using a knee tensor or balancer.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide an orthopedic instrument for kneearthroplasty that is configured to combine anterior-posterior (AP)femoral sizing and tension and balancing of the ligaments of a patient'sknee in one synergistically integrated orthopedic instrument rather thanusing two separate instruments. In some embodiments the orthopedicinstrument is unilateral, i.e., right/left knee specific. In someembodiments, the orthopedic instrument is universal and can be used forboth a right and a left knee.

In some embodiments, the orthopedic instrument includes ananterior-posterior (AP) sizer assembly, a tensor assembly and a rotationmechanism. The sizer assembly includes a stylus, a sizer body includingmedial and lateral posterior feet extending substantiallyperpendicularly from the sizer body, and a sizer slider that can sliderelative to the sizer body along a medial-lateral direction relative toa patient's knee for femoral sizing. The tensor assembly includes atensor frame having a central portion, medial and lateral wingsextending at an angle from the central portion, and medial and lateralposterior feet extending substantially perpendicularly to the centralportion. The rotation mechanism includes a portion coupled to the tensorframe of the tensor assembly and a portion coupled to the sizer body.The rotation mechanism is configured to rotate the medial and lateralposterior feet of the sizer body relative to the tensor frame toward alateral side of the patient's knee for balancing and tensioning the kneeligaments.

In some embodiments, the rotation mechanism is configured to beleft/right knee specific (unilateral). In some embodiments, the rotationmechanism is configured to be universal for both right and left knees.Two embodiments of the rotation mechanism of the universal integratedorthopedic instruments are provided.

In some embodiments, the orthopedic instrument is universal and includesan anterior-posterior sizer assembly and a tensor assembly. The sizerassembly includes a stylus, a sizer body having medial and lateralposterior feet extending substantially perpendicularly from the sizerbody, and a sizer slider slidable relative to the sizer body along amedial-lateral direction relative to a patient's knee. The sizer bodyhas a channel therethrough. The tensor assembly includes a tensor framehaving a central portion, medial and lateral wings extending at an anglefrom of the central portion, a tab extending from the central portionbetween the medial and lateral wings and having an elongated aperture,and medial and lateral posterior feet extending substantiallyperpendicularly to the central portion. The orthopedic instrument alsoincludes a plate having an angular scale on a first side and a recess ona second side opposite to the first side and facing the sizer body. Theorthopedic instrument also includes a knob rotatably received in therecess of the plate. The knob has a cam groove on a side facing thesizer body, and a cam slider supported in the channel of the sizer bodyand slidable in a medial-lateral direction within the channel of thesizer body. The cam slider includes a first post guidable by the camgroove of the knob and a second post movably received in the elongatedaperture of the tensor frame. Rotating the knob rotates the sizer bodyrelative to the tensor frame and changes a relative gap between thecorresponding posterior feet of the sizer body and the tensor frame totension the ligaments and balance the knee.

The present teachings also provide a method of sizing and balancing aknee for arthroplasty. The method includes placing an integratedorthopedic instrument for femoral sizing and ligament balancing incontact with a resected distal femoral surface of a femur of a patient'sknee in flexion, such that medial and lateral posterior feet of a tensorframe of the instrument are in contact with corresponding posteriorcondyles of the patient's femur and such that medial and lateralposterior feet of a sizer body of the instrument are positioned on aspacer placed on a resected proximal surface of the patient's tibia. Themethod includes securing first and second wings extending from a centralportion of the tensor frame on the resected distal femoral surface androtating the sizer body relative to the tensor frame via a rotationmechanism that connects the sizer body and the tensor frame to balancethe patient's ligaments in tension. The method includes sizing thepatient's femur by moving a stylus movably coupled to the sizer body onan anterior surface of the patient's femur.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a first isometric view of a unilateral integrated orthopedicinstrument according to the present teachings;

FIG. 2 is a second isometric view of the unilateral integratedorthopedic instrument of FIG. 1;

FIG. 3 is an exploded view of the unilateral integrated orthopedicinstrument of FIG. 1;

FIG. 4 is an isometric view of a component of a sizer assembly of theunilateral integrated orthopedic instrument of FIG. 1;

FIG. 5 is an isometric view of a portion of the rotation mechanism ofthe unilateral integrated orthopedic instrument of FIG. 1;

FIG. 6 is an isometric view of a portion of the rotation mechanism ofthe unilateral integrated orthopedic instrument of FIG. 1;

FIG. 6A is a partial sectional view of the rotation mechanism of theunilateral integrated orthopedic instrument of FIG. 1 shown in a firstposition;

FIG. 6B is a partial sectional view of the rotation mechanism of theunilateral integrated orthopedic instrument of FIG. 1 shown in a secondposition;

FIG. 7 is an environmental coronal view of the unilateral integratedorthopedic instrument of FIG. 1 shown on a left knee in flexion;

FIG. 8 is an environmental sagittal view of the unilateral integratedorthopedic instrument of FIG. 1 shown on a left knee in flexion;

FIG. 9 is a first isometric view of a universal integrated orthopedicinstrument according to the present teachings;

FIG. 10 is a second isometric view of the universal integratedorthopedic instrument of FIG. 9;

FIG. 11 is an exploded back view of the universal integrated orthopedicinstrument of FIG. 9;

FIG. 12 is an exploded front view of the universal integrated orthopedicinstrument of FIG. 9;

FIG. 13 is a detail of the exploded view of FIG. 12;

FIG. 14 is a detail of the exploded view of FIG. 11;

FIG. 15 is a sectional view of the universal integrated orthopedicinstrument of FIG. 9;

FIG. 16 is an environmental coronal view of the universal integratedorthopedic instrument of FIG. 9 shown on a left knee in flexion;

FIG. 17 is an environmental sagittal view of the universal integratedorthopedic instrument of FIG. 9 shown on a left knee in flexion;

FIG. 18 is a first isometric view of another universal integratedorthopedic instrument according to the present teachings;

FIG. 19 is a second isometric view of the universal integratedorthopedic instrument of FIG. 18;

FIG. 20 is an exploded view of a detail of the universal integratedorthopedic instrument of FIG. 18;

FIG. 21 is an assembled view of the detail of FIG. 20; and

FIG. 22 is an isometric view of a detail of the universal integratedorthopedic instrument of FIG. 18.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings. Example embodiments are provided so that thisdisclosure will be thorough, and will fully convey the scope to thosewho are skilled in the art. Numerous specific details are set forth suchas examples of specific components, devices, and methods, to provide athorough understanding of embodiments of the present disclosure. It willbe apparent to those skilled in the art that specific details need notbe employed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The present teachings are directed to various embodiments of anintegrated orthopedic instrument that can function and achieve theobjectives of both an AP sizer and a knee balancer in a single constructconfigured as an integrated, synergetic and enhanced construct thatreplaces two separate instruments for sizing and balancing. In someembodiments the orthopedic instrument is unilateral, i.e., right/leftknee specific. In some embodiments, the integrated orthopedic instrumentis universal and can be used for both a right and a left knee.

More specifically, FIGS. 1-8 illustrate various views and details of anexemplary embodiment of an integrated orthopedic instrument 100A. Theintegrated orthopedic instrument 100A is unilateral, i.e., configured tobe specific to a right or a left knee. The unilateral integratedorthopedic instrument 100A is illustrated for the left knee. Theunilateral integrated orthopedic instrument 100A for the right knee is amirror image of the unilateral integrated orthopedic instrument 100A forthe left knee. FIGS. 9-17 illustrate various views and details ofanother exemplary embodiment of an integrated orthopedic instrument100B. The integrated orthopedic instrument 100B is universal, i.e.,configured to be used with both a right knee and a left knee. FIGS.18-22 illustrate various views and details of another exemplaryuniversal integrated orthopedic instrument 100C. FIGS. 7 and 8 areenvironmental views of the unilateral integrated orthopedic instrument100A shown on a knee in flexion. FIGS. 16 and 17 are environmental viewsof the universal integrated orthopedic instrument 100B shown on a kneein flexion.

The unilateral and universal integrated orthopedic instruments 100A,100B, 100C have many elements in common. The common elements will bereferenced with the same numerals and will generally be described onlyonce in reference to the unilateral integrated orthopedic instrument100A. For example, the sizer stylus is referenced by the numeral 130 inboth the unilateral integrated orthopedic instrument 100A and theuniversal integrated orthopedic instruments 100B and 100C.

Referring to FIGS. 1-8, the unilateral integrated orthopedic instrument100A includes an AP (anterior-posterior) sizer assembly 102A for sizingthe femur and a tensor (or balancer) assembly 200 for tensioning theligaments and balancing the knee. The AP sizer assembly 102A isrotatably coupled to the tensor assembly 200 via a coupling rotationmechanism 250.

The AP sizer assembly 102A can include a sizer body 110A, a sizer slider120 and a sizer stylus 130. The sizer body 110A has an upper portion 112and a lower portion 116. The upper portion 112 can be U-shaped andinclude two pads 142. A rod 118 extends between the pads 142 and isspaced apart from the upper portion 112. The rod 118 may be modularlyconnected to the pads 142 such that the rod 118 can be detached andre-attached to the sizer body 110A by methods known in the art, such asremovable fasteners, press-fitting, taper connections, etc. The pads 142and the lower portion 116 form a planar surface 150 that can contact andengage a resected surface 94 of a distal end 92 of a femur 90 foranterior-posterior sizing of the femur 90. A base 146 extends from thelower portion 116 of the sizer body 110A. The base 146 defines aU-shaped recess 166 substantially parallel to the rod 118 and a channel170 perpendicular to the recess 166. The channel 170 is configured forconnection with the rotation mechanism 250 as discussed below. The sizerbody 110A includes a support portion 160 having first and second (medialand lateral) posterior feet or paddles 162 configured to contact andengage a spacer block 60 positioned on a resected surface 82 of a tibia80 during the procedure, as shown in FIG. 7. The first and secondposterior feet 162 of the sizer assembly 102A have equal thickness.

With continued reference to FIGS. 1-8, the sizer slider 120 of the APsizer assembly 102A has an L-shaped profile and a longitudinal bore 180.The sizer stylus 130 includes a stylus arm 132 terminating in a stylustip 134. The stylus arm 132 is coupled to a post 136 with an optionalsleeve 138. The post 136 is slidably and rotatably received in thelongitudinal bore 180. The stylus arm 132 can rotate about the bore 180with the post 136 or relatively to the post 136, such that the stylustip 134 can be brought in contact with any point on an anterior surface96 of the femur 90 for determining the size of the distal end 92 of thefemur 90. The sizer stylus 130 can slide axially with the sizer slider120 in the medial-lateral direction along the rod 118 to prevent softtissue impingement during sizing, especially in the anterior-lateralcorner, and to provide working space and clearance especially duringsmall incision knee procedures. A projection 190 of the sizer slider 120is received in the recess 166 of the sizer body 110A for sliding contactthereon. The sizer slider 120 also includes a through-hole 192 receivingthe rod 118. The sizer slider 120 can slide along the rod 118 along atrack defined by the recess 166. A calibrated linear scale 184 may bemarked, or imprinted, or otherwise affixed on a front face 182 of thesizer slider 120.

Referring to FIGS. 1-8, the tensor assembly 200 includes a tensor frame201 with a central portion 202 and first and second wings 204 extendingfrom and at an angle relative to the central portion 202. The centralportion 202 and the first and second wings 204 define a substantiallyplanar surface 206 configured to contact the resected surface 94 of thedistal end 92 of the femur 90 and be coplanar with the surface 150 ofthe sizer body 110A, as shown in FIG. 8. First and second (medial andlateral) posterior feet or paddles 210M, 210L extend from the tensorframe 201 substantially perpendicularly to the planar surface 206. Theposterior feet 210L, 210M of the tensor assembly 200 have differentthicknesses. Specifically, the lateral posterior foot 210L has a greaterthickness “t” that the thickness of the medial posterior foot 210M, suchthat in the assembled unilateral integrated orthopedic instrument 100A,there is a gap “g” between the medial posterior foot 162 of the sizerassembly 102A and the medial posterior foot of the tensor assembly 200.The gap g allows tensioning and balancing of the knee ligaments when thesizer body 110A is rotated relative to the tensor frame 201 by therotation mechanism 250.

Referring to FIGS. 3 through 6B, the rotation mechanism 250 includesinteracting portions of the tensor frame 201, the sizer body 110A and acam mechanism that includes first and second cam components 260 and 270.The first cam component 260 includes a cam body 262 and a cam arm 264extending from the cam body 262 and having a cam post 266. The secondcam component (or cam guide) includes a circular plate or dial knob 272having first and second faces 282, 284 on opposite sides of a curvedperipheral wall 288. A shaft or handle 274 extends outward from thesecond face 284. The first face 282 includes a curved cam groove 276that receives and guides the cam post 266. The second face 284 includesan angular scale 286. The knob 272 includes flute-like or scallop-likeformations 278 along a portion of the peripheral wall 288. The tensorframe 201 includes a cam housing 220 extending from the central portion202 on a side opposite to the medial posterior foot 210M. The camhousing 220 includes a peripheral wall 222 with two curved slots 224forming a spring with a spring arm 226 with formations 228 that engagethe formations 278 of the knob 272. The spring arm 226 stabilizes andprovides tactile feedback the position of knob 272 as the knob 272 isrotated toward the lateral side in incremental angles indicated on theangular scale 286. A distal portion of the cam arm 264 is positioned ina cutout space 230 formed between two walls 232, 234 of the housing 220.The cam body 262 of the cam component 260 is received in the channel 170of the sizer body 110A. Referring to FIGS. 2, 4, 6A and 6B, when theknob 272 is rotated, the cam post 266 moves along the curved cam groove276 exerting a rotation moment through the arm 264 to the cam body 262and to the sizer body 110A toward the lateral side, thereby reducing thegap g (FIG. 2) to an amount required to balance ligament tension andequalize the gaps between the lateral and medial posterior condyles 98L,98M of the knee joint relative to the tibia 70.

Referring to FIG. 1, the angular scale 286 is calibrated to show theangle of relative rotation between the posterior feet 162 of the APsizer body 110A and the posterior feet 210M, 210L of the tensor assembly200, or generally the relative rotation between the sizer body 110A andthe tensor frame 201. For example, if the actual rotation angle of theknob 272 is “x” and the relative rotation between the AP sizer body 110Aand the tensor frame 201 is “y”, then a rotation transmission ratio isequal to “x” divided by “y”. In the embodiment of illustrated in FIGS.1-8, a rotation transmission ratio of about 15 is used. Generally, arotation transmission ratio of about 5 to about 20 can be used.

Referring to FIGS. 7 and 8, after the distal end 92 of the femur 90 isresected, the unilateral integrated orthopedic instrument 100A isattached to the distal end 92. Specifically, the tensor frame 201 of thetensor assembly 200 is attached to the resected surface 94 of the femur90 using fasteners through holes 207 in the wings 204. The posteriorfeet 210M, 210L of the tensor frame 201 are engaged in direct contactwith the corresponding medial and lateral posterior condyles 98M, 98L ofthe femur 90, and the surface 206 of the tensor frame 201 and thesurface 150 of the sizer body 110A are in direct contact with theresected surface 94 of the femur 90. The posterior feet 162 of the sizerbody 110A are supported on the spacer 60 positioned on the resectedsurface 82 of the tibia 80. The knob 272 is turned toward the lateralside of the femur 90 such that the sizer body 110A and, in particular,the posterior feet 162 of the sizer body 110A rotate relative to theposterior feet 210M, 210L of the tensor frame 201, (which is attached tothe resected surface 94 of the femur 90) about pivot axis P until theligaments of the knee joint are balanced in tension. The pivot axis Pdefined by a bolt 203 that rotatably couples the tensor frame 201 andthe cam body 262 of the cam component 260. After balancing, the sizerbody 110A can also be fixed on the resected surface 94 with fastenersand used to determine the size of the femur 90.

The sizer slider 120 can slide relatively to the sizer body 110A in themedial-lateral direction to avoid tissue impingement during sizing. Thearm 132 of the stylus 130 can be rotated, such that the stylus tip 134contacts the anterior surface 96 of the femur 90. Several readings maybe taken on the scale 184 as the stylus tip 134 moves about the anteriorsurface 96 by observing the position of an indicator (not shown)relative to the scale 184. The size of the femur 90 is determined by thehighest reading on the scale 184. During the movement of the stylus 130,the sizer slider 120 may be moved medially or laterally to accommodatethe movement of the stylus 130 without causing tissue impingement. Itshould be noted that femoral sizing can also be done before ligamentbalancing, or repeated after ligament balancing for an additionalconfirmation.

Referring to FIGS. 9-17, a first embodiment of the universal integratedorthopedic instrument 100B is illustrated. The universal integratedorthopedic instrument 100B is configured to be used in both the rightand left knee instead of using right and left knee unilateral integratedorthopedic instruments, such as the unilateral integrated orthopedicinstrument 100A for the left knee and a unilateral integrated orthopedicinstrument (mirror image of 100A) for the right knee. The universalintegrated orthopedic instrument 100B includes an AP(anterior-posterior) sizer assembly 102B for sizing the femur and atensor (or balancer) assembly 400 for tensioning the ligaments andbalancing the knee. The AP sizer assembly 102B is rotatably coupled tothe tensor assembly 400 via a coupling rotation mechanism 500. The APsizer assembly 102B shares many elements with the AP sizer assembly 102Aof the unilateral integrated orthopedic instrument 100A. The elementsthat are substantially identical are referenced with the same numeralsand their description is not repeated. Differences between similarelements will be pointed out.

Referring to FIGS. 9-17, the tensor assembly 400 includes a tensor frame401 with a central portion 402, first and second wings 404 extendingfrom and at an angle relative to the central portion 402 and a tab orflange 408 extending from the central portion 402 perpendicularly to thecentral portion 402 and positioned symmetrically between the first andsecond wings 404. The central portion 402, the flange 408 and the firstand second wings 404 define a substantially planar surface 406configured to contact the resected surface 94 of the distal end 92 ofthe femur 90, as shown in FIG. 17. First and second (medial and lateral)posterior feet or paddles 410 extend from the tensor frame 401substantially perpendicularly to the planar surface 406. Unlike theposterior feet 210M, 210L of the tensor assembly 200 of the unilateralintegrated orthopedic instrument 100A, the posterior feet 410 of thetensor assembly 400 have the same thickness. In this respect, equal gaps“g” are formed between the posterior feet 162 of the sizer assembly 102Band the posterior feet of the tensor assembly 400, as shown in FIG. 10.The gaps g allow tensioning and balancing of the knee ligaments when thesizer assembly 102B is rotated relative to the tensor assembly 400 bythe rotation mechanism 500 toward the lateral side of the knee joint,whether the universal integrated orthopedic instrument 100B is attachedon the left or the right knee of the patient.

The AP sizer assembly 102B can also include a sizer body 110B, a sizerslider 120 and a sizer stylus 130. The sizer body 110B is modified fromthe sizer body 110A to accommodate the different tensor assembly 400 androtation mechanism 500 for the universal (right and left knee) use ofthe universal integrated orthopedic instrument 100B. More specifically,the sizer body 110B has a U-shaped upper portion 112 that includes twopads 142 and a lower portion 116B that is recessed from the upperportion 112. As in the sizer body 110A of the unilateral integratedorthopedic instrument 100A, a rod 118 extends between the pads 142 andis spaced apart from the upper portion 112. Similarly, a base 146extends from the lower portion 116B of the sizer body 110B. The basedefines a U-shaped recess 166 substantially parallel to the rod 118. Achannel 170B extends through the sizer body 110B and the base 146perpendicularly to the recess 166. A projection 190 of the sizer slider120 is received in the recess 166 for sliding contact thereon. The sizerslider 120 also includes a through-hole 192 receiving the rod 118. Thesizer slider 120 can slide along the rod 118 and along a track definedby the recess 166. The channel 170B is configured for connection withthe rotation mechanism 500 as discussed below.

Referring to FIGS. 11-15, the rotation mechanism 500 includes a plate550, a rotatable dial or knob 560, a spring 570, a cam slider 580 andcorresponding coupling portions of the tensor frame 401 and the sizerbody 110B. The knob 560 includes a curved groove or cam guide 562 thatis configured to receive and guide a cam post 582 (first post 582) thatextends from a body 584 of the cam slider 580 at an offset(non-symmetrically) relative to the body 584 and toward the knob 560(see also FIG. 13). The knob 560 includes a shaft 564 with a driverformation 566 configured to engage a driver for rotating the knob 560and an angular scale 561 (see also FIGS. 12 and 13). The knob 560 alsoincludes flute- or scallop-type formations 563 along a portion of aperipheral wall 565 of the knob 560.

With continued reference to FIGS. 11-15, the plate 550 includes a recess552 formed substantially as a circular sector and configured forreceiving a portion of the knob 560, as shown, for example, in theassembled view of FIG. 9. The recess 552 is bounded by a curved wallportion 556 having a center slot 558 oriented substantiallyperpendicularly to the plane defined by the body of the plate 550 (seeFIG. 14). The shaft 564 of the knob passes through an opening 554 of theplate 550 such that the driver formations 566 are accessible during theprocedure.

With continued reference to FIGS. 11-15, the body 584 of the cam slider580 is configured to be movably received in the channel 170B of the APsizer body 110B with clearance such that the body 584 of the cam slider580 can slide along one or more pins or rods 590 that pass throughcorresponding bores 586 of cam slider 580 (see FIGS. 11 and 13). Thisdegree of freedom contributes to a rotation transmission ratio discussedbelow. The pins 590 span the medial-lateral width of the channel 170Band are supported on the AP sizer body 110B. A second post 588 having acircular cross-section extends asymmetrically from the slider body 584toward the tensor frame 401 and is movably received in an elongatedaperture 409 of the tensor frame 401. The elongated aperture 409provides clearance such that the second post 588 can move along theaperture 409 and contributes to the rotation transmission ratiodiscussed below.

The spring 570 of the rotation mechanism 500 has a body 572 with a slot574 forming a flexible leaf 576 with a finger 578 extending toward theknob 560, such that the finger 578 can be engaged to and disengaged fromthe flute formations 563 on the knob 560 and provide resistance andtactile and/or audible feedback when the knob 560 is rotated by the user(see FIG. 14).

Summarizing the operation of the rotation mechanism 500, a driver (notshown) can be used to engage the driver formations 566 of the knob 560and rotate the knob 560 toward the lateral side of the right or leftknee. The medical professional can be guided by the scale 561 andreceive a tactile and/or audible feedback, as discussed above, by theinteraction of the finger 578 of the spring 570 with the fluteformations 563 of the knob 560. The rotation is transmitted from theknob 560 through the cam post 582 to the cam slider 580 and from the camslider 580 the AP sizer body 110B. The AP sizer body 110B is rotatablycoupled to the tensor frame 401 via a pivot bolt 403 defining a pivotaxis P that passes through a pivot hole 405. The second post 588 of thecam slider 580 is received in the elongated aperture 409 of the tensorframe 401 such that a moment is transmitted from the second post 588 torotate the AP sizer body 110B relative to the tensor frame 401. Themotion of the cam post 582 of the cam slider 580 along the cam groove562 of the knob 560, the travel of the cam slider 580 along the pins 590in the channel 170B of the sizer body 110B, and the travel of the secondpost 588 along the elongated aperture 409 of the tensor frame 401 of thetensor assembly 400 provide a predetermined rotation transmission ratiobetween the rotation of the knob 560, and the relative rotation betweenthe posterior feet 162 of the AP sizer body 110B and the posterior feet410 of the tensor assembly 400 (or generally between the sizer body 110Band the sizer frame 401), as shown on the angular scale 561 (see FIGS. 9and 14). The angular scale 561 is calibrated to show the angle ofrelative rotation between the posterior feet 162 of the AP sizer body110B and the posterior feet 410 of the tensor assembly 400. For example,if the actual rotation angle of the knob 560 is “x” and the relativerotation between the AP sizer body 110B and the tensor frame 401 is “y”,then the rotation transmission ratio is “x” divided by “y”. In theembodiment of the universal integrated instrument illustrated in FIGS.9-17, a rotation transmission ratio is about 6.7. Generally, a rotationtransmission ratio of about 5 to about 20 can be used. Accordingly,graduated and controlled balancing of the ligaments can be achieved. Theresected femur can then be sized using the AP sizer assembly 102B asdiscussed above in connection with the unilateral integrated orthopedicinstrument 100A.

Referring to FIGS. 18-22, another embodiment of the universal integratedorthopedic instrument 100C is illustrated. The universal integratedorthopedic instrument 100C includes an AP (anterior-posterior) sizerassembly 102C for sizing the femur, a tensor (or balancer) assembly 400Cfor tensioning the ligaments and balancing the knee and a rotationmechanism 600. The AP sizer assembly 102C is rotatably coupled to thetensor assembly 400C via the rotation mechanism 600. The AP sizerassembly 102C can also include a sizer body 110C, a sizer slider 120 anda sizer stylus 130. The sizer body 110C has a U-shaped upper portion 112that includes two pads 142 and a lower portion 116C that is recessedfrom the upper portion 112 for receiving a flange 408 of a tensor frame401 of the tensor assembly 400C. A rod 118 extends between the pads 142and is spaced apart from the upper portion 112. Similarly, a base 146Cextends from the lower portion 116C of the sizer body 110C. The base146C defines a U-shaped recess 166 substantially parallel to the rod118. A projection 190 of the sizer slider 120 is received in the recess166 for sliding contact thereon. The sizer slider 120 also includes athrough-hole 192 receiving the rod 118. The sizer slider 120 can slidealong the rod 118 and along a track defined by the recess 166. Thisembodiment is similar to the universal integrated orthopedic instrument100B, except for the rotation mechanism 600 which provides a directrotation transmission. The rotation mechanism 600 includes a plate 650attached to an AP sizer body 110C, a pivot bolt 620 along a pivot axis Pand a set screw 630 for controlling the rotation (see FIGS. 18 and 22).The pivot bolt 620 can be rotated with a driver using driver formations622, shown in FIG. 18. The pivot bolt 620 passes through a hole 163 ofthe AP sizer body 110C and a corresponding hole 405 of the tensor frame401. A set screw 630 with driver formations 632 passes from the plate650 through a threaded hole 167 of the AP sizer body 116C. The set screw630 can be driven from the plate 650 using a driver to engage the driverformation 632 until the set screw 630 engages the tensor frame 401 andprevents further rotation (see FIG. 18).

As discussed above, the present teachings provide various embodiments ofan integrated orthopedic instrument that can be used to replace separateAP sizer and tensor balancing instruments used in knee arthroplasty.Each integrated instrument of the present teachings is not merely anaddition of separate instruments, but has components customized to oneanother to work synergistically and provide a single instrument for thesurgeon. In this respect, an AP sizer assembly and a tensor assembly arecustomized to work as a single unit having a separate but correspondingpairs of posterior feet and a rotation mechanism integrally coupled tothe AP sizer assembly and the tensor assembly such that one of the pairsof posterior feet can rotate relative to the other for ligamenttensioning and knee balancing. In one embodiment, a unilateralintegrated orthopedic instrument is provided, i.e., an integratedorthopedic instrument customized to be used with only one of a patient'stwo knees, such as a left knee, for example, and a similar mirror imagefor the opposite knee, i.e., the right knee. In another embodiment, auniversal integrated orthopedic instrument is provided, i.e., anintegrated orthopedic instrument customized to be used for both a leftknee and a right knee. Two examples of universal integrated orthopedicinstruments are provided having different rotation mechanisms anddifferent types of rotation control, including rotation transmissioncontrol.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. An orthopedic instrument for knee arthroplastycomprising: an anterior-posterior femoral sizer assembly having astylus, a sizer body including medial and lateral posterior feetextending substantially perpendicularly from the sizer body, and a sizerslider slidable relative to the sizer body along a medial-lateraldirection relative to a patient's knee; a tensor assembly including atensor frame having a central portion, medial and lateral wingsextending at an angle from the central portion, and medial and lateralposterior feet extending in a plane that is substantially perpendicularto the central portion and the medial and lateral wings; and a rotationmechanism including a portion coupled to the tensor frame of the tensorassembly and a portion coupled to the sizer body, the rotation mechanismconfigured to rotate the medial and lateral posterior feet of the sizerbody relative to the tensor frame toward a lateral side of the patient'sknee; wherein the rotation mechanism includes a plate supporting a pivotbolt, the pivot bolt passing through the sizer body and through thecentral portion of the tensor frame of the tensor assembly, the pivotbolt configured to rotate the sizer body relative to the tensor frame.2. The orthopedic instrument of claim 1, further comprising a set screwextending from the plate through the sizer body and engageable to a tabextending from the central portion of the tensor frame, the set screwconfigured for constraining relative rotation between the sizer body andthe tensor frame.
 3. The orthopedic instrument of claim 1, wherein therotation mechanism is configured for ligament balancing for both a rightknee and a left knee.